[kiterunner]

I've been wanting to do this for so long, but I never realised it was possible until I saw it just now on the Genea-Musings blog. You can get a list of ancestry's tree hints for any individual database. First, get the tree number, which will show in the URL when you go to your ancestry tree. Then, get the database number, which will show in the URL if you go to the search page for the particular database that you want (for example, the 1939 Register, or whatever). Then type the following URL into the address bar:
https://www.ancestry.co.uk/hints/tree/your tree number/hints?hf=record&hs=last&hdbid=database number
Press return and you should get the list of hints for that database. Should be particularly useful when they add a new database, but should work for any which has hints.